Maurizio Mencuccini

Plasticity in leaf‐level water relations of tropical rainforest trees in response to experimental drought

Publisher: Wiley

Date: 22-03-2016

DOI: 10.1111/NPH.13927

Abstract: The tropics are predicted to become warmer and drier, and understanding the sensitivity of tree species to drought is important for characterizing the risk to forests of climate change. This study makes use of a long‐term drought experiment in the Amazon rainforest to evaluate the role of leaf‐level water relations, leaf anatomy and their plasticity in response to drought in six tree genera. The variables (osmotic potential at full turgor, turgor loss point, capacitance, elastic modulus, relative water content and saturated water content) were compared between seasons and between plots (control and through‐fall exclusion) enabling a comparison between short‐ and long‐term plasticity in traits. Leaf anatomical traits were correlated with water relation parameters to determine whether water relations differed among tissues. The key findings were: osmotic adjustment occurred in response to the long‐term drought treatment species resistant to drought stress showed less osmotic adjustment than drought‐sensitive species and water relation traits were correlated with tissue properties, especially the thickness of the abaxial epidermis and the spongy mesophyll. These findings demonstrate that cell‐level water relation traits can acclimate to long‐term water stress, and highlight the limitations of extrapolating the results of short‐term studies to temporal scales associated with climate change.

Death from drought in tropical forests is triggered by hydraulics not carbon starvation

Publisher: Springer Science and Business Media LLC

Date: 23-11-2015

DOI: 10.1038/NATURE15539

Abstract: Drought threatens tropical rainforests over seasonal to decadal timescales, but the drivers of tree mortality following drought remain poorly understood. It has been suggested that reduced availability of non-structural carbohydrates (NSC) critically increases mortality risk through insufficient carbon supply to metabolism ('carbon starvation'). However, little is known about how NSC stores are affected by drought, especially over the long term, and whether they are more important than hydraulic processes in determining drought-induced mortality. Using data from the world's longest-running experimental drought study in tropical rainforest (in the Brazilian Amazon), we test whether carbon starvation or deterioration of the water-conducting pathways from soil to leaf trigger tree mortality. Biomass loss from mortality in the experimentally droughted forest increased substantially after >10 years of reduced soil moisture availability. The mortality signal was dominated by the death of large trees, which were at a much greater risk of hydraulic deterioration than smaller trees. However, we find no evidence that the droughted trees suffered carbon starvation, as their NSC concentrations were similar to those of non-droughted trees, and growth rates did not decline in either living or dying trees. Our results indicate that hydraulics, rather than carbon starvation, triggers tree death from drought in tropical rainforest.

Limited acclimation in leaf anatomy to experimental drought in tropical rainforest trees

Publisher: Oxford University Press (OUP)

Date: 10-09-2016

DOI: 10.1093/TREEPHYS/TPW078

Quaternary climate change explains global patterns of tree beta-diversity

Publisher: Cold Spring Harbor Laboratory

Date: 17-11-2020

DOI: 10.1101/2020.11.14.382846

Abstract: Both historical and contemporary environmental conditions determine present bio ersity patterns, but their relative importance is not well understood. One way to disentangle their relative effects is to assess how different dimensions of beta- ersity relate to past climatic changes, i.e., taxonomic, phylogenetic and functional compositional dissimilarity, and their components generated by replacement of species, lineages and traits (turnover) and richness changes (nestedness). Here, we quantify global patterns of each of these aspects of beta- ersity among neighboring sites for angiosperm trees using the most extensive global database of tree species-distributions (43,635 species). We found that temperature change since the Last Glacial Maximum (LGM) was the major influence on both turnover and nestedness components of beta- ersity, with a negative correlation to turnover and a positive correlation to nestedness. Moreover, phylogenetic and functional nestedness was higher than expected from taxonomic beta- ersity in regions that experienced large temperature changes since the LGM. This pattern reflects relatively greater losses of phylogenetic and functional ersity in species-poor assemblages, possibly caused by phylogenetically and functionally selective species extinction and recolonization during glacial-interglacial oscillations. Our results send a strong warning that rapid anthropogenic climate change is likely to result in a long-lasting phylogenetic and functional compositional simplification, potentially impairing forest ecosystem functioning.

Paleoclimate and current climate collectively shape the phylogenetic and functional diversity of trees worldwide

Publisher: Cold Spring Harbor Laboratory

Date: 03-06-2020

DOI: 10.1101/2020.06.02.128975

Abstract: Trees are of vital importance for ecosystem functioning and services at local to global scales, yet we still lack a detailed overview of the global patterns of tree ersity and the underlying drivers, particularly the imprint of paleoclimate. Here, we present the high-resolution (110 km) worldwide mapping of tree species richness, functional and phylogenetic ersities based on ∼7 million quality-assessed occurrences for 46,752 tree species (80.5% of the estimated total number of tree species), and subsequent assessments of the influence of paleo-climate legacies on these patterns. All three tree ersity dimensions exhibited the expected latitudinal decline. Contemporary climate emerged as the strongest driver of all ersity patterns, with Pleistocene and deeper-time ( 7 years) paleoclimate as important co-determinants, and, notably, with past cold and drought stress being linked to reduced current ersity. These findings demonstrate that tree ersity is affected by paleoclimate millions of years back in time and highlight the potential for tree ersity losses from future climate change.

Drought stress and tree size determine stem CO₂ efflux in a tropical forest

Publisher: Wiley

Date: 03-02-2018

DOI: 10.1111/NPH.15024

Respiration in wood: integrating across tissues, functions and scales

Publisher: Wiley

Date: 24-12-2020

DOI: 10.1111/NPH.16354

Half of the world’s tree biodiversity is unprotected and is increasingly threatened by human activities

Publisher: Cold Spring Harbor Laboratory

Date: 23-04-2020

DOI: 10.1101/2020.04.21.052464

Abstract: Although trees are key to ecosystem functioning, many forests and tree species across the globe face strong threats. Preserving areas of high bio ersity is a core priority for conservation however, different dimensions of bio ersity and varied conservation targets make it difficult to respond effectively to this challenge. Here, we ( i ) identify priority areas for global tree conservation using comprehensive coverage of tree ersity based on taxonomy, phylogeny, and functional traits and ( ii ) compare these findings to existing protected areas and global bio ersity conservation frameworks. We find that ca . 51% of the top-priority areas for tree bio ersity are located in current protected areas. The remaining half top-priority areas are subject to moderate to high human pressures, indicating conservation actions are needed to mitigate these human impacts. Our findings emphasize the effectiveness of using tree conservation priority areas for future global conservation planning.

Drought‐related tree mortality: addressing the gaps in understanding and prediction

Publisher: Wiley

Date: 27-03-2015

DOI: 10.1111/NPH.13382

Abstract: Increased tree mortality during and after drought has become a research focus in recent years. This focus has been driven by: the realisation that drought-related tree mortality is more widespread than previously thought the predicted increase in the frequency of climate extremes this century and the recognition that current vegetation models do not predict drought-related tree mortality and forest dieback well despite the large potential effects of these processes on species composition and biogeochemical cycling. To date, the emphasis has been on understanding the causal mechanisms of drought-related tree mortality, and on mechanistic models of plant function and vegetation dynamics, but a consensus on those mechanisms has yet to emerge. In order to generate new hypotheses and to help advance the modelling of vegetation dynamics in the face of incomplete mechanistic understanding, we suggest that general patterns should be distilled from the erse and as-yet inconclusive results of existing studies, and more use should be made of optimisation and probabilistic modelling approaches that have been successfully applied elsewhere in plant ecology. The outcome should inform new empirical studies of tree mortality, help improve its prediction and reduce model complexity.

Stomatal optimization based on xylem hydraulics (SOX) improves land surface model simulation of vegetation responses to climate

Publisher: Wiley

Date: 17-02-2020

DOI: 10.1111/NPH.16419

Weak tradeoff between xylem safety and xylem‐specific hydraulic efficiency across the world's woody plant species

Publisher: Wiley

Date: 17-09-2015

DOI: 10.1111/NPH.13646

Abstract: The evolution of lignified xylem allowed for the efficient transport of water under tension, but also exposed the vascular network to the risk of gas emboli and the spread of gas between xylem conduits, thus impeding sap transport to the leaves. A well‐known hypothesis proposes that the safety of xylem (its ability to resist embolism formation and spread) should trade off against xylem efficiency (its capacity to transport water). We tested this safety–efficiency hypothesis in branch xylem across 335 angiosperm and 89 gymnosperm species. Safety was considered at three levels: the xylem water potentials where 12%, 50% and 88% of maximal conductivity are lost. Although correlations between safety and efficiency were weak ( r 2 0.086), no species had high efficiency and high safety, supporting the idea for a safety–efficiency tradeoff. However, many species had low efficiency and low safety. Species with low efficiency and low safety were weakly associated ( r 2 0.02 in most cases) with higher wood density, lower leaf‐ to sapwood‐area and shorter stature. There appears to be no persuasive explanation for the considerable number of species with both low efficiency and low safety. These species represent a real challenge for understanding the evolution of xylem.

Harvesting water from unsaturated atmospheres: deliquescence of salt secreted onto leaf surfaces drives reverse sap flow in a dominant arid climate mangrove, Avicennia marina

Publisher: Wiley

Date: 12-06-2021

DOI: 10.1111/NPH.17461

Abstract: The mangrove Avicennia marina adjusts internal salt concentrations by foliar salt secretion. Deliquescence of accumulated salt causes leaf wetting that may provide a water source for salt‐secreting plants in arid coastal wetlands where high nocturnal humidity can usually support deliquescence whereas rainfall events are rare. We tested the hypotheses that salt deliquescence on leaf surfaces can drive top‐down rehydration, and that such absorption of moisture from unsaturated atmospheres makes a functional contribution to dry season shoot water balances. Sap flow and water relations were monitored to assess the uptake of atmospheric water by branches during shoot wetting events under natural and manipulated microclimatic conditions. Reverse sap flow rates increased with increasing relative humidity from 70% to 89%, consistent with function of salt deliquescence in harvesting moisture from unsaturated atmospheres. Top‐down rehydration elevated branch water potentials above those possible from root water uptake, subsidising transpiration rates and reducing branch vulnerability to hydraulic failure in the subsequent photoperiod. Absorption of atmospheric moisture harvested through deliquescence of salt on leaf surfaces enhances water balances of Avicennia marina growing in hypersaline wetlands under arid climatic conditions. Top‐down rehydration from these frequent, low intensity wetting events contributes to prevention of carbon starvation and hydraulic failure during drought.

Rainforest trees respond to drought by modifying their hydraulic architecture

Publisher: Wiley

Date: 12-2018

DOI: 10.1002/ECE3.4601

Plant traits controlling growth change in response to a drier climate

Publisher: Wiley

Date: 06-11-2020

DOI: 10.1111/NPH.16972

Abstract: Plant traits are increasingly being used to improve prediction of plant function, including plant demography. However, the capability of plant traits to predict demographic rates remains uncertain, particularly in the context of trees experiencing a changing climate. Here we present data combining 17 plant traits associated with plant structure, metabolism and hydraulic status, with measurements of long‐term mean, maximum and relative growth rates for 176 trees from the world’s longest running tropical forest drought experiment. We demonstrate that plant traits can predict mean annual tree growth rates with moderate explanatory power. However, only combinations of traits associated more directly with plant functional processes, rather than more commonly employed traits like wood density or leaf mass per area, yield the power to predict growth. Critically, we observe a shift from growth being controlled by traits related to carbon cycling (assimilation and respiration) in well‐watered trees, to traits relating to plant hydraulic stress in drought‐stressed trees. We also demonstrate that even with a very comprehensive set of plant traits and growth data on large numbers of tropical trees, considerable uncertainty remains in directly interpreting the mechanisms through which traits influence performance in tropical forests.

Linking hydraulic traits to tropical forest function in a size-structured and trait-driven model (TFS v.1-Hydro)

Publisher: Copernicus GmbH

Date: 24-11-2016

DOI: 10.5194/GMD-9-4227-2016

Abstract: Abstract. Forest ecosystem models based on heuristic water stress functions poorly predict tropical forest response to drought partly because they do not capture the ersity of hydraulic traits (including variation in tree size) observed in tropical forests. We developed a continuous porous media approach to modeling plant hydraulics in which all parameters of the constitutive equations are biologically interpretable and measurable plant hydraulic traits (e.g., turgor loss point πtlp, bulk elastic modulus ε, hydraulic capacitance Cft, xylem hydraulic conductivity ks,max, water potential at 50 % loss of conductivity for both xylem (P50,x) and stomata (P50,gs), and the leaf : sapwood area ratio Al : As). We embedded this plant hydraulics model within a trait forest simulator (TFS) that models light environments of in idual trees and their upper boundary conditions (transpiration), as well as providing a means for parameterizing variation in hydraulic traits among in iduals. We synthesized literature and existing databases to parameterize all hydraulic traits as a function of stem and leaf traits, including wood density (WD), leaf mass per area (LMA), and photosynthetic capacity (Amax), and evaluated the coupled model (called TFS v.1-Hydro) predictions, against observed diurnal and seasonal variability in stem and leaf water potential as well as stand-scaled sap flux. Our hydraulic trait synthesis revealed coordination among leaf and xylem hydraulic traits and statistically significant relationships of most hydraulic traits with more easily measured plant traits. Using the most informative empirical trait–trait relationships derived from this synthesis, TFS v.1-Hydro successfully captured in idual variation in leaf and stem water potential due to increasing tree size and light environment, with model representation of hydraulic architecture and plant traits exerting primary and secondary controls, respectively, on the fidelity of model predictions. The plant hydraulics model made substantial improvements to simulations of total ecosystem transpiration. Remaining uncertainties and limitations of the trait paradigm for plant hydraulics modeling are highlighted.

Detecting forest response to droughts with global observations of vegetation water content

Publisher: Wiley

Date: 25-09-2021

DOI: 10.1111/GCB.15872

Abstract: Droughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil‐plant‐atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more. Unlike water potential, which requires demanding in situ measurements, VWC can be retrieved from remote sensing measurements, particularly at microwave frequencies using radar and radiometry. Here, we highlight key frontiers through which VWC has the potential to significantly increase our understanding of forest responses to water stress. To validate remote sensing observations of VWC at landscape scale and to better relate them to data assimilation model parameters, we introduce an ecosystem‐scale analog of the pressure–volume curve, the non‐linear relationship between average leaf or branch water potential and water content commonly used in plant hydraulics. The sources of variability in these ecosystem‐scale pressure‐volume curves and their relationship to forest response to water stress are discussed. We further show to what extent diel, seasonal, and decadal dynamics of VWC reflect variations in different processes relating the tree response to water stress. VWC can also be used for inferring belowground conditions—which are difficult to impossible to observe directly. Lastly, we discuss how a dedicated geostationary spaceborne observational system for VWC, when combined with existing datasets, can capture diel and seasonal water dynamics to advance the science and applications of global forest vulnerability to future droughts.

The Ecosystem Pressure-Volume Curve

Publisher: Cold Spring Harbor Laboratory

Date: 14-09-2022

DOI: 10.1101/2022.09.12.507627

Abstract: The ecosystem pressure-volume curve (EPV) is the relationship between vegetation water content and a representative value of water potential applied on a ground-area basis. The EPV attempts to reconcile our detailed and physically rigorous understanding of small-scale field-measureable processes to the spatial scale applicable to ecosystem and climate science. Successfully bridging that gap in scale potentially allows us to use field measurements to interpret remote sensing data, and then remote sensing data to inform our understanding of vegetation-climate interactions. Here we clearly define the idea of the EPV, evaluate the limitations of applying values of water content and water potential to ecosystems on a ground area basis, and discuss practical ways to construct the EPV with existing data. We also present the first EPVs based on data from nine different plots, including tropical rainforest, savanna, temperate forest, and a long-term drought experiment in Amazonian rainforest (Caxiuanã, State of Pará, Brazil). The initial findings suggest high levels of consistency among sites. In particular, the ratio of water to biomass across ecosystems appears to be constrained to around 1:3. Seven of nine sites had closely converging ‘relative maximum water storage’ (the proportion of total stored water than can be lost before an ecosystem succumbs to physiological damage) at 9.1% +/-1.8 standard deviation. Relative ecosystem capacitance may increase with site biomass ( P = 0.091), but varied little across sites with a mean of 0.068 MPa −1 +/-0.029 standard deviation. These first estimates suggest that the EPV idea may reveal useful trends across ecosystems, potentially paving the way to increasing the ecophysiological significance of remote sensing data, and enabling an alternative method for modelling long-term ecosystem-climate feedbacks based on equilibrium thermodynamics.

An empirical method that separates irreversible stem radial growth from bark water content changes in trees: theory and case studies

Publisher: Wiley

Date: 06-01-2017

DOI: 10.1111/PCE.12863

Global convergence in the vulnerability of forests to drought

Publisher: Springer Science and Business Media LLC

Date: 11-2012

DOI: 10.1038/NATURE11688

Abstract: Shifts in rainfall patterns and increasing temperatures associated with climate change are likely to cause widespread forest decline in regions where droughts are predicted to increase in duration and severity. One primary cause of productivity loss and plant mortality during drought is hydraulic failure. Drought stress creates trapped gas emboli in the water transport system, which reduces the ability of plants to supply water to leaves for photosynthetic gas exchange and can ultimately result in desiccation and mortality. At present we lack a clear picture of how thresholds to hydraulic failure vary across a broad range of species and environments, despite many in idual experiments. Here we draw together published and unpublished data on the vulnerability of the transport system to drought-induced embolism for a large number of woody species, with a view to examining the likely consequences of climate change for forest biomes. We show that 70% of 226 forest species from 81 sites worldwide operate with narrow (<1 megapascal) hydraulic safety margins against injurious levels of drought stress and therefore potentially face long-term reductions in productivity and survival if temperature and aridity increase as predicted for many regions across the globe. Safety margins are largely independent of mean annual precipitation, showing that there is global convergence in the vulnerability of forests to drought, with all forest biomes equally vulnerable to hydraulic failure regardless of their current rainfall environment. These findings provide insight into why drought-induced forest decline is occurring not only in arid regions but also in wet forests not normally considered at drought risk.

The impact of soil microorganisms on the global budget of δ ¹⁸ O in atmospheric CO ₂

Publisher: Proceedings of the National Academy of Sciences

Date: 29-12-2009

DOI: 10.1073/PNAS.0905210106

Abstract: Improved global estimates of terrestrial photosynthesis and respiration are critical for predicting the rate of change in atmospheric CO 2 . The oxygen isotopic composition of atmospheric CO 2 can be used to estimate these fluxes because oxygen isotopic exchange between CO 2 and water creates distinct isotopic flux signatures. The enzyme carbonic anhydrase (CA) is known to accelerate this exchange in leaves, but the possibility of CA activity in soils is commonly neglected. Here, we report widespread accelerated soil CO 2 hydration. Exchange was 10–300 times faster than the uncatalyzed rate, consistent with typical population sizes for CA-containing soil microorganisms. Including accelerated soil hydration in global model simulations modifies contributions from soil and foliage to the global CO 18 O budget and eliminates persistent discrepancies existing between model and atmospheric observations. This enhanced soil hydration also increases the differences between the isotopic signatures of photosynthesis and respiration, particularly in the tropics, increasing the precision of CO 2 gross fluxes obtained by using the δ 18 O of atmospheric CO 2 by 50%.

Plumbing the depths: extracellular water storage in specialized leaf structures and its functional expression in a three-domain pressure –volume relationship

Publisher: Wiley

Date: 25-07-2017

DOI: 10.1111/PCE.12788

Abstract: A three-domain pressure-volume relationship (PV curve) was studied in relation to leaf anatomical structure during dehydration in the grey mangrove, Avicennia marina. In domain 1, relative water content (RWC) declined 13% with 0.85 MPa decrease in leaf water potential, reflecting a decrease in extracellular water stored primarily in trichomes and petiolar cisternae. In domain 2, RWC decreased by another 12% with a further reduction in leaf water potential to -5.1 MPa, the turgor loss point. Given the osmotic potential at full turgor (-4.2 MPa) and the effective modulus of elasticity (~40 MPa), domain 2 emphasized the role of cell wall elasticity in conserving cellular hydration during leaf water loss. Domain 3 was dominated by osmotic effects and characterized by plasmolysis in most tissues and cell types without cell wall collapse. Extracellular and cellular water storage could support an evaporation rate of 1 mmol m

Stand dynamics modulate water cycling and mortality risk in droughted tropical forest

Publisher: Wiley

Date: 09-2017

DOI: 10.1111/GCB.13851

Abstract: Transpiration from the Amazon rainforest generates an essential water source at a global and local scale. However, changes in rainforest function with climate change can disrupt this process, causing significant reductions in precipitation across Amazonia, and potentially at a global scale. We report the only study of forest transpiration following a long-term (>10 year) experimental drought treatment in Amazonian forest. After 15 years of receiving half the normal rainfall, drought-related tree mortality caused total forest transpiration to decrease by 30%. However, the surviving droughted trees maintained or increased transpiration because of reduced competition for water and increased light availability, which is consistent with increased growth rates. Consequently, the amount of water supplied as rainfall reaching the soil and directly recycled as transpiration increased to 100%. This value was 25% greater than for adjacent nondroughted forest. If these drought conditions were accompanied by a modest increase in temperature (e.g., 1.5°C), water demand would exceed supply, making the forest more prone to increased tree mortality.

Linking vegetation to climate using ecosystem pressure-volume relationships

Publisher: Authorea, Inc.

Date: 27-02-2023

DOI: 10.22541/AU.167750170.06051289/V1

Abstract: Water potential is the principal driving force for the movement of water through soils and plants, and directly influences plant physiological responses. The relationships between water potential and water content in plants and soil have long been of interest, and there is increasing focus on understanding how these fundamental measures of water are linked at larger spatial and temporal scales. In this Perspective, we explore how the theory of pressure-volume relationships can be applied at ecosystem scale. We define and evaluate the concept and limitations of the ecosystem pressure-volume curve (EPV), and discuss practical ways to construct EPVs with existing data. EPVs were generated from equilibrium water potentials and water content of the above ground biomass of nine plots including tropical rainforest, savanna, temperate forest, and a long-term Amazonian rainforest drought experiment. Initial findings suggest high levels of consistency among sites where the steady-state ratio of water:biomass appears to be approximately 1:3, while ecosystem values of relative hydraulic capacitance and accessible water storage do not vary systematically with biomass. The EPV reveals useful trends across ecosystems, providing a thermodynamically consistent steady-state view of ecosystem form and function, and a biophysically robust basis for the interpretation of microwave remote sensing data.

A multi-species synthesis of physiological mechanisms in drought-induced tree mortality

Publisher: Springer Science and Business Media LLC

Date: 07-08-2017

DOI: 10.1038/S41559-017-0248-X

Abstract: Widespread tree mortality associated with drought has been observed on all forested continents and global change is expected to exacerbate vegetation vulnerability. Forest mortality has implications for future biosphere-atmosphere interactions of carbon, water and energy balance, and is poorly represented in dynamic vegetation models. Reducing uncertainty requires improved mortality projections founded on robust physiological processes. However, the proposed mechanisms of drought-induced mortality, including hydraulic failure and carbon starvation, are unresolved. A growing number of empirical studies have investigated these mechanisms, but data have not been consistently analysed across species and biomes using a standardized physiological framework. Here, we show that xylem hydraulic failure was ubiquitous across multiple tree taxa at drought-induced mortality. All species assessed had 60% or higher loss of xylem hydraulic conductivity, consistent with proposed theoretical and modelled survival thresholds. We found erse responses in non-structural carbohydrate reserves at mortality, indicating that evidence supporting carbon starvation was not universal. Reduced non-structural carbohydrates were more common for gymnosperms than angiosperms, associated with xylem hydraulic vulnerability, and may have a role in reducing hydraulic function. Our finding that hydraulic failure at drought-induced mortality was persistent across species indicates that substantial improvement in vegetation modelling can be achieved using thresholds in hydraulic function.

Mechanisms of woody-plant mortality under rising drought, CO2 and vapour pressure deficit

Publisher: Springer Science and Business Media LLC

Date: 29-03-2022

DOI: 10.1038/S43017-022-00272-1

The global spectrum of plant form and function: enhanced species-level trait dataset

Publisher: Springer Science and Business Media LLC

Date: 07-12-2022

DOI: 10.1038/S41597-022-01774-9

Abstract: Here we provide the ‘Global Spectrum of Plant Form and Function Dataset’, containing species mean values for six vascular plant traits. Together, these traits –plant height, stem specific density, leaf area, leaf mass per area, leaf nitrogen content per dry mass, and diaspore (seed or spore) mass – define the primary axes of variation in plant form and function. The dataset is based on ca. 1 million trait records received via the TRY database (representing ca. 2,500 original publications) and additional unpublished data. It provides 92,159 species mean values for the six traits, covering 46,047 species. The data are complemented by higher-level taxonomic classification and six categorical traits (woodiness, growth form, succulence, adaptation to terrestrial or aquatic habitats, nutrition type and leaf type). Data quality management is based on a probabilistic approach combined with comprehensive validation against expert knowledge and external information. Intense data acquisition and thorough quality control produced the largest and, to our knowledge, most accurate compilation of empirically observed vascular plant species mean traits to date.

TRY plant trait database – enhanced coverage and open access

Publisher: Wiley

Date: 31-12-2019

DOI: 10.1111/GCB.14904

Abstract: Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to bio ersity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on in idual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.

Assimilation of repeated woody biomass observations constrains decadal ecosystem carbon cycle uncertainty in aggrading forests

Publisher: American Geophysical Union (AGU)

Date: 03-2017

DOI: 10.1002/2016JG003520

Rooting depth and xylem vulnerability are independent woody plant traits jointly selected by aridity, seasonality, and water table depth

Publisher: Wiley

Date: 24-09-2023

DOI: 10.1111/NPH.19276

Modelling tropical forest responses to drought and El Niño with a stomatal optimization model based on xylem hydraulics

Publisher: The Royal Society

Date: 08-10-2018

DOI: 10.1098/RSTB.2017.0315

Abstract: The current generation of dynamic global vegetation models (DGVMs) lacks a mechanistic representation of vegetation responses to soil drought, impairing their ability to accurately predict Earth system responses to future climate scenarios and climatic anomalies, such as El Niño events. We propose a simple numerical approach to model plant responses to drought coupling stomatal optimality theory and plant hydraulics that can be used in dynamic global vegetation models (DGVMs). The model is validated against stand-scale forest transpiration ( E ) observations from a long-term soil drought experiment and used to predict the response of three Amazonian forest sites to climatic anomalies during the twentieth century. We show that our stomatal optimization model produces realistic stomatal responses to environmental conditions and can accurately simulate how tropical forest E responds to seasonal, and even long-term soil drought. Our model predicts a stronger cumulative effect of climatic anomalies in Amazon forest sites exposed to soil drought during El Niño years than can be captured by alternative empirical drought representation schemes. The contrasting responses between our model and empirical drought factors highlight the utility of hydraulically-based stomatal optimization models to represent vegetation responses to drought and climatic anomalies in DGVMs. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

Leaf economics and plant hydraulics drive leaf : wood area ratios

Publisher: Wiley

Date: 15-07-2019

DOI: 10.1111/NPH.15998

Abstract: Biomass and area ratios between leaves, stems and roots regulate many physiological and ecological processes. The Huber value H

The BRAIN Initiative Cell Census Network Data Ecosystem: A User’s Guide

Publisher: Cold Spring Harbor Laboratory

Date: 30-10-2022

DOI: 10.1101/2022.10.26.513573

Abstract: Characterizing cellular ersity at different levels of biological organization across data modalities is a prerequisite to understanding the function of cell types in the brain. Classification of neurons is also required to manipulate cell types in controlled ways, and to understand their variation and vulnerability in brain disorders. The BRAIN Initiative Cell Census Network (BICCN) is an integrated network of data generating centers, data archives and data standards developers, with the goal of systematic multimodal brain cell type profiling and characterization. Emphasis of the BICCN is on the whole mouse brain and demonstration of prototypes for human and non-human primate (NHP) brains. Here, we provide a guide to the cellular and spatial approaches employed, and to accessing and using the BICCN data and its extensive resources, including the BRAIN Cell Data Center (BCDC) which serves to manage and integrate data across the ecosystem. We illustrate the power of the BICCN data ecosystem through vignettes highlighting several BICCN analysis and visualization tools. Finally, we present emerging standards that have been developed or adopted by the BICCN toward FAIR (Wilkinson et al. 2016a) neuroscience. The combined BICCN ecosystem provides a comprehensive resource for the exploration and analysis of cell types in the brain.

Global beta-diversity of angiosperm trees is shaped by Quaternary climate change

Publisher: American Association for the Advancement of Science (AAAS)

Date: 05-04-2023

DOI: 10.1126/SCIADV.ADD8553

Abstract: As Earth’s climate has varied strongly through geological time, studying the impacts of past climate change on bio ersity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in bio ersity. Here, we assessed the influence of Quaternary climate change on spatial dissimilarity in taxonomic, phylogenetic, and functional composition among neighboring 200-kilometer cells (beta- ersity) for angiosperm trees worldwide. We found that larger glacial-interglacial temperature change was strongly associated with lower spatial turnover (species replacements) and higher nestedness (richness changes) components of beta- ersity across all three bio ersity facets. Moreover, phylogenetic and functional turnover was lower and nestedness higher than random expectations based on taxonomic beta- ersity in regions that experienced large temperature change, reflecting phylogenetically and functionally selective processes in species replacement, extinction, and colonization during glacial-interglacial oscillations. Our results suggest that future human-driven climate change could cause local homogenization and reduction in taxonomic, phylogenetic, and functional ersity of angiosperm trees worldwide.

Tree size and climatic water deficit control root to shoot ratio in individual trees globally

Publisher: Wiley

Date: 23-10-2017

DOI: 10.1111/NPH.14863

Vapour pressure deficit modulates hydraulic function and structure of tropical rainforests under nonlimiting soil water supply

Publisher: Wiley

Date: 14-09-2023

DOI: 10.1111/NPH.19257

Forest system hydraulic conductance: partitioning tree and soil components

Publisher: Wiley

Date: 20-12-2021

DOI: 10.1111/NPH.17895

Abstract: Soil–leaf hydraulic conductance determines canopy–atmosphere coupling in vegetation models, but it is typically derived from ex‐situ measurements of stem segments and soil s les. Using a novel approach, we derive robust in‐situ estimates for whole‐tree conductance ( k tree ), ‘functional’ soil conductance ( k soil ), and ‘system’ conductance ( k system , water table to canopy), at two climatically different tropical rainforest sites. Hydraulic ‘functional rooting depth’, determined for each tree using profiles of soil water potential (Ψ soil ) and sap flux data, enabled a robust determination of k tree and k soil . k tree was compared across species, size classes, seasons, height above nearest drainage (HAND), two field sites, and to alternative representations of k tree k soil was analysed with respect to variations in site, season and HAND. k tree was lower and changed seasonally at the site with higher vapour pressure deficit (VPD) and rainfall k tree differed little across species but scaled with tree circumference r soil (1/ k soil ) ranged from 0 in the wet season to 10× less than r tree (1/ k tree ) in the dry season. VPD and not rainfall may influence plot‐level k leaf water potentials and sap flux can be used to determine k tree , k soil and k system Ψ soil profiles can provide mechanistic insights into ecosystem‐level water fluxes.

High exposure of global tree diversity to human pressure

Publisher: Proceedings of the National Academy of Sciences

Date: 16-06-2022

DOI: 10.1073/PNAS.2026733119

Abstract: Safeguarding Earth’s tree ersity is a conservation priority due to the importance of trees for bio ersity and ecosystem functions and services such as carbon sequestration. Here, we improve the foundation for effective conservation of global tree ersity by analyzing a recently developed database of tree species covering 46,752 species. We quantify range protection and anthropogenic pressures for each species and develop conservation priorities across taxonomic, phylogenetic, and functional ersity dimensions. We also assess the effectiveness of several influential proposed conservation prioritization frameworks to protect the top 17% and top 50% of tree priority areas. We find that an average of 50.2% of a tree species’ range occurs in 110-km grid cells without any protected areas (PAs), with 6,377 small-range tree species fully unprotected, and that 83% of tree species experience nonnegligible human pressure across their range on average. Protecting high-priority areas for the top 17% and 50% priority thresholds would increase the average protected proportion of each tree species’ range to 65.5% and 82.6%, respectively, leaving many fewer species (2,151 and 2,010) completely unprotected. The priority areas identified for trees match well to the Global 200 Ecoregions framework, revealing that priority areas for trees would in large part also optimize protection for terrestrial bio ersity overall. Based on range estimates for ,000 tree species, our findings show that a large proportion of tree species receive limited protection by current PAs and are under substantial human pressure. Improved protection of bio ersity overall would also strongly benefit global tree ersity.

Short-term effects of drought on tropical forest do not fully predict impacts of repeated or long-term drought: gas exchange versus growth

Publisher: The Royal Society

Date: 08-10-2018

DOI: 10.1098/RSTB.2017.0311

Abstract: Are short-term responses by tropical rainforest to drought (e.g. during El Niño) sufficient to predict changes over the long-term, or from repeated drought? Using the world's only long-term (16-year) drought experiment in tropical forest we examine predictability from short-term measurements (1–2 years). Transpiration was maximized in droughted forest: it consumed all available throughfall throughout the 16 years of study. Leaf photosynthetic capacity was maintained, but only when averaged across tree size groups. Annual transpiration in droughted forest was less than in control, with initial reductions (at high biomass) imposed by foliar stomatal control. Tree mortality increased after year three, leading to an overall biomass loss of 40% over the long-term, the main constraint on transpiration was thus imposed by the associated reduction in sapwood area. Altered tree mortality risk may prove predictable from soil and plant hydraulics, but additional monitoring is needed to test whether future biomass will stabilize or collapse. Allocation of assimilate differed over time: stem growth and reproductive output declined in the short-term, but following mortality-related changes in resource availability, both showed long-term resilience, with partial or full recovery. Understanding and simulation of these phenomena and related trade-offs in allocation will advance more effectively through greater use of optimization and probabilistic modelling approaches. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

The University Of Edinburgh

Location: United Kingdom of Great Britain and Northern Ireland

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University Of North Carolina At Charlotte

Location: United States of America

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Kitware Inc

Location: United States of America

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CREAF - Centre De Recerca Ecològica I Aplicacions Forestals

Location: Spain

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Institució Catalana De Recerca I Estudis Avançats (ICREA)

Location: Spain

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University Of Florence

Location: Italy

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Discovery Projects - Grant ID: DP180102969

Start Date: 05-2018

End Date: 12-2021

Amount: $368,400.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP130104092

Start Date: 2013

End Date: 12-2017

Amount: $365,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP150104437

Start Date: 06-2015

End Date: 06-2018

Amount: $428,900.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP170104091

Start Date: 06-2017

End Date: 12-2020

Amount: $448,000.00

Funder: Australian Research Council